The invention relates to landfill systems which include an excavation in which waste is disposed. In particular, the invention is directed to protecting a geomembrane in a landfill system by including a composite geo mat that is highly effective in resisting puncture.
Municipal landfill systems typically utilize a landfill in which solid wastes are disposed. The landfill system typically includes an excavation which is lined with a geomembrane. Sand is then placed in the bottom of the excavation on top of the geomembrane to protect against puncture from metal, rocks, wood, or other solid debris and waste placed in the excavation. Typically, three or more feet of protective cover sand is utilized in the excavation to protect against puncture of the geomembrane. While sand is utilized in the bottom of the excavation to protect against puncture, it is difficult to protect the sides of the excavation. Even though most of the weight is on the bottom of the geomembrane, it is also desirable to protect against the puncture of sides. The cost of cover sand is also expensive.
Previously, various arrangements of composite mats have been proposed for use in different applications. For example, U.S. Pat. No. 3,252,251 discloses the idea of using a geotextile mat comprising a woven fabric and a laminated plastic layer for use in a plant bed. U.S. Pat. No. 4,219,600 discloses a wood pulp, fabric layer having a plastic film backing used as a moisturizing mat. U.S. Pat. No. 5,090,154 discloses a ground cover having a polyurethane/polyethylene layer laminated with a composite layer which includes a woven fiberglass fabric filled with an asphalt filler. U.S. Pat. No. 5,091,247 discloses a woven geotextile fabric having a plastic coating for earth reinforcement applications.
It is also known to place a backing of rubber onto a cloth backing such as shown in U.S. Pat. Nos. 2,853,399 and 2,915,427. However, these applications are generally not related to landfill systems, nor puncture resistance. Chipped rubber mats have been utilized in many applications which are typically formed from a mixing chipped rubber and urethane, and molding the mixture into a product. It has also been known to form or mold a cube from shredded tire rubber and liquid urethane, and slice the material into thin layers for use as mats. However, none of the-previous prior art mats and structures are satisfactory for use in a landfill system.
Accordingly, an object of the invention is to provide a highly effective puncture protection mat for use in protecting a geomembrane in a landfill system.
Another object of the invention is to provide a composite mat which comprises a geotextile layer and an extruded thermoplastic layer bonded to the geotextile fabric formed from dispersed rubber particles.
Another object of the invention is to provide a composite mat for use in landfill systems which includes a geotextile fabric layer, and an extruded layer bonded to the geotextile layer which is extruded from a composition composed of recycled tire rubber, an extrusion agent, and a performance additive to provide a highly effective laminated mat construction having improved puncture resistant characteristic.
Another object of the invention is to provide a landfill system wherein a geomembrane lining of the landfill system is protected from puncture without the use of sand and the like by utilizing a highly effective puncture protection mat overlying the geomembrane.